Eight-cylinder printing machines use four printing couples, in which a first, second, third and fourth rubber blanket cylinder, each, is in engagement with a plate cylinder. To provide for dual-image prime and verso (2/2) printing, a substrate, for example a web of paper is passed between a first and second rubber blanket cylinder, and then, spaced therefrom, a third and fourth rubber blanket cylinder.
For some installations, it is desired to provide only one printing image on a specific side, for example the verso side, whereas two color images are desired on the opposite or prime side. The referenced textbook "Techniken, Systeme, Maschinen" ("Technology, Systems, Machines") by Oskar Frei, published by Polygraphverlag, page 11, FIG. 21, picture 4, describes a printing system having four printing couples. To obtain, as described in the textbook, 2/1 printing or 1/2 printing, that is, only a single image on one side of the web, it is necessary to disengage a plate-blanket pair from printing effectiveness. One of the blanket cylinders, however, will be required to form an impression cylinder for that one of the sides which requires dual image printing. This results in serious disadvantages since the plate cylinder, which is not needed and which frequently is driven, then must be disengaged from the blanket cylinder which is needed as the impression cylinder for the second prime image. Inkers and dampers associated with the plate cylinder likewise have to be disengaged. Of course, the situation can be reversed or the mirror-image printing arrangement may be required, namely one image on the prime side and a double image on the verso side. What has been said above is, of course, equally applicable thereto